Skin (not detailed)

• What is the stratum spinosum composed of?

  8 – 10 layers of polygonal cells
• Why is the stratum spinosum also called the 'prickle cell layer'?

  It has thorn-like projections from cell surface
• What is the primary function of the stratum spinosum?

  Provide strength and flexibility to the skin
• How many layers does the stratum granulosum have?

  3 – 5 layers of flattening cells
• What do the 'grains' in the stratum granulosum represent?

  Early form of the protein keratin
• What happens to cells in the stratum granulosum?

  They begin to lose their nuclei and die
• How many layers are in the stratum lucidum?

  3 – 5 layers of closely packed clear cells
• Where is the stratum lucidum more pronounced?

  In the skin of fingertips, palms, and soles
• What is the outer layer of the epidermis called?

  Stratum corneum
• How many layers does the stratum corneum have?

  20 – 30 layers of flattened cells
• What is the primary function of the stratum corneum?

  Forms a barrier to light, heat, and chemicals
• How long does it take for the complete replacement of the epidermis?

  1 month
• What are the main components of the dermis?

  • Tough and elastic connective tissue
  • Contains blood vessels, nerves, glands, hair follicles
  • Has two main layers: papillary and reticular
• What type of tissue is the papillary layer of the dermis made of?

  Areolar connective tissue
• What is the function of dermal papillae?

  Increase surface area and create fingerprints
• What do Meissner’s corpuscles sense?

  Light touch
• What do free nerve endings in the papillary layer sense?

  Warmth, coolness, pain, tickling, and itching
• What type of connective tissue is found in the reticular layer of the dermis?

  Dense, irregular connective tissue
• What do Pacinian corpuscles sense?

  Deep pressure and vibration
• What are the functions of the dermis?

  • Provides strength and elasticity to the skin
  • Contains blood vessels and nerves
  • Houses glands and hair follicles
• What is the subcutaneous layer also known as?

  Hypodermis or subcutis
• What is the primary function of the subcutaneous layer?

  Storage depot for fat
• What is the surface area of the skin in adults?

  About 1.5 – 2 m²
• What systems is the skin part of?

  The integumentary system
• What are the functions of the skin?

  • Protection against microbes and chemicals
  • Helps control body temperature
  • Excretion of substances like salt and urea
  • Formation of vitamin D
  • Contains sensory receptors
• What do Merkel cells sense?

  Light touch and aid shape determination
• What do Langerhans cells do?

  Alert the immune system to antigens
• What is the difference between hairy and glabrous skin?

  Glabrous skin is non-hairy, like palms
• What type of epithelium is the epidermis composed of?

  Keratinised stratified squamous epithelium
• What is the thickest part of the epidermis?

  Soles of feet and palms of hands
• What is the stratum basale also known as?

  Basal cell layer
• What is the primary function of the stratum basale?

  Continuous cell division and stem cell production
• What do melanocytes produce?

  The pigment melanin
• What are freckles?

  Patch of melanocytes in the skin
• What layer of skin is most sensitive to radiation?

  Stratum basale